The present invention generally relates to snow plow assemblies and, more particularly, to snow plow assemblies that employ tripping mechanisms.
Snow plow assemblies are commonly mounted onto a variety of vehicles during winter months in an effort to efficiently remove snow from paths, sidewalks, roadways, and other areas. Vehicles onto which these assemblies may be mounted include garden and heavy-duty tractors, light-duty and heavy-duty trucks (such as those adapted to spread sand and salt), and maintenance vehicles such as "Bobcats." These assemblies commonly employ a blade or moldboard in a forward position. The moldboard is typically mounted onto a frame, with the frame in turn being mounted onto the front of the vehicle. As the vehicle moves forward, the moldboard contacts the snow and causes that snow to be displaced to one or both sides of the moldboard, thereby clearing the snow from the surface over which the moldboard passes. Examples of conventional snow plow assemblies are provided in U.S. Pat. Nos. 4,215,494, 5,109,618, 5,121,562, and 5,191,727.
During the plowing of snow, the moldboard is typically positioned so that its lower edge contacts and slides along, or is held just above, the road or other surface being plowed. Of course, roads, driveways, parking lots and other surfaces may be irregular, and may further contain protruding rocks, ice chunks, or other debris embedded therein. These irregularities potentially create problems, for when the lower edge of a moldboard strikes an irregularity or other immovable object, the force of the impact may damage the moldboard, the frame, or in some cases the vehicle itself. In order to protect the moldboard, frame assembly and vehicle from damage during use, it is known to mount the moldboard, or the lower portion thereof, pivotally so that the moldboard (or lower portion thereof) can "trip" or move when it strikes a rigidly fixed or immovable object, thus allowing the moldboard to pass over the object, and thereby hopefully avoiding any significant damage to the assembly. After the moldboard passes the object, a biasing force, typically provided by a spring, biases the moldboard back into its normal plowing position.
While various configurations have been employed for biasing a pivotable moldboard, the biasing force provided by many of these configurations is often not optimal for more than one set of operating conditions. This creates a problem when a vehicle is assigned to remove snow from a variety of surfaces, each having a different surface condition, or in changing environmental conditions. While there exist some snow plow assemblies that do provide for some degree of adjustment of a biasing force, these assemblies are complicated mechanically, and are not relatively easily and quickly adjustable by a vehicle operator after the vehicle leaves the garage. Thus, there exists a need for a snow plow assembly which overcomes the aforesaid and other problems associated with existing assemblies.